Patent GB-892011-A (GB)
Title: Jet propelled helicopter
IPC: B64C27/32
Filed: 1958-03-04
Abstract: 892,011. Helicopters. LAING, N., HEIDELBERG, G. ECK, B., and LUDIN, L. March 4, 1958, No. 37809/57. Class 4 [Also in Groups XXVI and XXVII] A jet-propelled helicopter comprises a power source and a bladed rotor mounted on the fuselage and normally driven by reason of power developed in the power source wherein each rotor blade is hollow and has at its rear edge a slot extending inwardly from adjacent the blade tip and a flap is pivotally mounted at each slot to extend therealong and to control the direction of the jet issuing from the slot under the action of control means which moves the flaps cyclically and collectively, the power source functioning to develop operating pressure in the hollow blade for the production of said jet, which operating pressure is so low that in autorotation of the rotor upon failure of the power source the pressure produced by the rotor pump effect averaged over the length of the slot is sufficiently close to said operating pressure similarly averaged that the helicopter may still be controlled by said control means without the necessity for a change of blade angle, air entering the interior of the hollow blades encountering little resistance in autorotation of the rotor. The rotor comprises a pair of fixed hollow blades each provided along the outer two-thirds of the trailing edge with a slot 106, Fig. 1c, having a flap 107, of uniform chord pivoted adjacent its lower rearward edge 108. Provision is made over the trailing portion of the blade for drawing in boundary layer air. The interior of the blades communicate with a blower positioned either in the fuselage or part way along the span of each blade, the output of the blower being such that the volume and pressure of gas delivered thereby is sufficiently close to that delivered by the combined output of the blower and the rotor pump effect resulting from centrifugal action during rotation that effective control of the helicopter may be maintained under all operating conditions. In Fig. 5a the body 500 supports a shaft 502 rigid with the casing 504 of a gas turbine engine 503. The rotor hub 505 is mounted on the turbine casing by hollow arms 505a and supports a pair of hollow blades 506 the root portion 507 of which are rigid with hub 505 and the hollow portions 508 carrying the trailing edge slots are mounted on the root portions by leaf springs (not shown) to pivot slightly in vertical planes, pressure tight seals 510 and droop stops 511 being provided. The turbine of engine 503 drives directly a shaft 512 which, through planetary gearing 513 drives a double centrifugal fan 514 which draws air through upper and lower intakes 526 and 527 and delivers it radially into the rotor blades, the airflow being augmented by residual jet efflux delivered from the engine 503 through hollow arms 505a. The fan unit is so constructed that it offers little resistance to airflow through the fan and rotor blades during autorotation of the rotor. In apparatus for adjusting flaps 107 cyclically and collectively, shown diagramatically in Fig. 7, the flap is mounted on a shaft 711 which is urged into a position of maximum flap lift coefficient by a coil spring 713 or a torsion bar. The shaft carries a pair of rectangular vanes 709, 710 enclosed respectively within sectorshaped casings 708a and 708b. The leading edge portion 701 of each rotor blade has an enlargement or land 700 wherein are formed three openings 702, 703 and 704, the opening 703 being on the chord-line and the other two being disposed on either side thereof at 45 degrees to the chord line. The openings 702, 703, 704 are connected respectively by conduits 705, 706, 707 to the lower chamber of casing 708b, the upper chamber of casing 708a and the upper chamber of easing 708b so that vane 709 is subjected to the dynamic pressure at opening 703 urging the flap to a minimum lift coefficient position and vane 710 is subjected on opposite sides to the dynamic pressures at openings 702, 704. The lower chamber of casing 708a carries one pipe 720 which leads to a position on the rotor blade where rotor pump pressure will apply suction to the lower chamber and another pipe 721 which connects through conduit 714 to the pilot-operated control means shown in Fig. 12. In this a distributor D comprises a casing 1215 closed at its upper end and rotating coaxially with the rotor hub and formed with connections for pipes 1214 which connect with the pipes 714 shown in Fig. 7 and with a central non-rotating block 1216 which closes the lower end of the casing and is formed with four outward-facing cavities 1217, 1218, 1219 and 1220 which, as the casing rotates each come periodically opposite the pipes 1214. A throttle valve assembly V comprises a block formed with three similar parallel bores 1221, 1222 and 1250 each closed at each end and containing respectively pistons 1225, 1226 and 1238. The central bore 1250 is slotted at 1242 to communicate with atmosphere, the slot being masked by the piston 1238 under the control of a pilot operated lever 1240 whereby the air supply to the lower chambers of casing 708a may be adjusted simultaneously and collectively. The pistons 1225 and 1226 are adjusted by a control lever 1229 to mask or unmask ports connecting slot 1242 through pipes (shown diagramatically) to the cavities 1217-1220 whereby the air supply to said lower chambers is adjusted cyclically. In a further embodiment, Fig. 13 (not shown), the collective control is provided by a single valve, the cylinders 1221 and 1222 being combined with distributor D in the form of a single swash-plate type of valve. Various devices are described for adjusting the trailing edge flaps automatically in accordance with ambient conditions, Figs. 8-11 and 15 (not shown). Devices for controlling the helicopter in yaw are described, one comprising a fan mounted within a ducting ring which may be moved as a unit axially of the fan axis within a housing to control the airflow therethrough. The fan is coupled to the rotor drive and the variation in loading on the fan results in application of torque about the rotor shaft; In another device a fore and aft rotary impeller is mounted at the rear end of the fuselage which imposes a side force to the rear end of the fuselage in opposition to rotor torque. A resilient mounting for the rotor head is described, Fig. 25 (not shown), with provision for adjusting the inclination of the lift vector. Specifications 876,611 and 870,612 are referred to.